J. Appl. Hort., 2(2):117-118, July-December, 2000
Inheritance of yield and its attributing characters in pumpkin
(Cucurbita moschata Duch ex. Poir)
P.S. Sirohi and T.K. Behera
Division of Vegetable Crops, Indian Agricultural Research Institute, New Delhi – 110 012, INDIA
Abstract
Twenty eight F1 hybrids involving 8 distinct genotypes (parents) in half diallel fashion were evaluated to study the gene action of yield
and its contributing characters in pumpkin (Cucurbita moschata Duch ex. Poir). Dominant gene action was observed for all the
characters, viz., vine length, fruit maturity, fruits per plant, fruit weight and yield per plant. In all these characters, dominance (H1)
component of variance was greater than additive (D) component of variance. The heritability in narrow sense was found to be less
than 0.50 for majority of characters. Low narrow sense of heritability coupled with higher degree of non-additive gene action (dominance
variance) in yield and its components suggested that heterosis breeding might be advantageous for obtaining higher gains in pumpkin.
Key words: Quantitative inheritance, pumpkin, Cucurbita moschata, genetics of yield, yield components.
Introduction
Pumpkin (Cucurbita moschata Duch ex Poir) occupies prominent
position among the cultivated cucurbitaceous vegetables because
of its higher yield, nutritive value, good storability, long period of
availability and better transport qualities. Yield is the pre-requisite
for improvement of any crop. In pumpkin, the genetic potentiality
is practically unexplored though wide range of genetic variability
is available in this crop in India. A comprehensive knowledge of
the genetic architecture of valuable genotypes is essential to exploit
them profitably in breeding programme. Hence, the diallel analysis
the quickest and widely adopted approach was employed to study
the inheritance pattern of yield and its attributes in this crop.
Materials and methods
characters studied. This indicated that both additive and nonadditive gene actions were involved in the expression of yield
and its components. However, the dominance component of
variation was found to be higher than additive component of
variation for all the characters.
Table 1. Estimates of components of variation and some
statistical parameters for yield and its attributes
Statistics
Vine
Fruit Fruits Fruit Yield
length
maturity /plant weight /plant
(cm)
(days) (No.) (kg)
(kg)
Ê
0.01
0.19
0.01
0.00
0.99
D̂
1.30*
10.47
0.19*
1.86*
5.75*
F̂
1.78
6.70
0.00
0.98
5.44
Ĥ1
3.38*
44.84*
0.85*
2.35*
27.31*
Ĥ 2
2.38*
29.63*
0.77*
2.06* 23.69**
ĥ2
0.87*
2.29
0.12
1.59
23.73*
( Hˆ / Dˆ )1/ 2
1.61
2.07
2.14
1.12
2.18
H 2 / 4 Hˆ 2
0.18
0.17
0.23
0.22
0.22
The experimental material comprised of 8 genetically diverse
lines of pumpkin namely, Pusa Vishwas, S-107-B, S-124-10,
NDPK-24, S-15, S-12, S-20 and S-17. These 8 lines were crossed
in a half diallel fashion and 28 F1 hybrids were obtained. Twenty
eight F1 hybrids with 8 parents were grown in a randomised
block design with 3 replications. The observations were made
on vine length (cm), fruit maturity (days), fruits/plant, fruit weight
(kg) and yield/plant (kg). The crop is grown at a spacing of 0.75
m between plants and 4 m between the channels. Ten plants in
each genotype were used for taking observations. The
components of variation were calculated as per the methods given
by Jinks and Hayman (1953), Hayman (1954) and Aksel and
Johnson (1963).
(4 Dˆ Hˆ 1 )1/ 2 + Fˆ )
2.47
(4 Dˆ Hˆ 1 )1/ 2 − Fˆ )
1.36
1.00
1.61
1.59
hˆ2 / Hˆ 2
0.365
0.077
0.156
0.77
1.00
Results and discussion
S2
0.08
30.42
0.00
0.06
3.39
H 2 (ns )
0.43
0.21
0.17
0.57
0.20
The estimates of the components of variation for the yield and
its attributes are presented in Table 1. It revealed from the present
study that the additive (D) component of variance was found to
be significant for vine length (1.30), fruits per plant (0.19), fruit
weight (1.86) and yield per plants (5.75) where as the dominance
component of variance (H1) was found significant for all the
b ± SE (b)
0.560
0.077
0.417 0.078 1.129
+0.350
+0.069 +0.268 +0.360 +0.350
t2
0.0035
47.54
0.54
1.73
2.11
** Significant at 1% level, * Significant at 5% level
118
Journal of Applied Horticulture
The average degree of dominance (H1/D)½ was found to be
greater than one for vine length (1.61), fruit maturity (2.07),
fruits per plant (2.14), fruit weight (1.12) and yield per plant
(2.18). These two conditions indicated the role of overdominance gene action for all the characters studied. The
proportion of genes with positive and negative effects (H2/4 H1)
in the parents was found to be less than 0.25 for all the characters
indicating unequal distribution of positive and negative alleles
among the parents. The ratio of dominant and recessive genes in
the parents { (4 DH1)½ + F/(4 DH1)½ -F} was greater than unity
for all the characters except fruits per plant which showed excess
of dominant genes in the parents.
Low narrow sense heritability coupled with over dominance for
vine length, fruit maturity, fruits per plant, yield per plant
indicated non-additive components in controlling these traits.
Doijode and Sulladmath (1985) reported similar results for days
to fruit maturity. Sirohi et al. (1986) observed over dominance
gene action for vine length, fruits per plant, yield per plant in
pumpkin. These results are in agreement with present study. Gill
et al (1971) observed non-additive gene action for number of
fruit per plant in summer squash (Cucurbita pepo) and Janakiram
and Sirohi (1991) observed similar results in bottle gourd. The
predominance of non-additive gene action and low to moderate
narrow sense of heritability for the characters suggested that the
heterosis breeding would be effective for the improvement of
these traits in pumpkin.
References
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characters in pumpkin (Cucurbita moschata). Egypt. J. Gent. Cytol.,
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Gill, H.S., J.P. Singh and Ram Singh, 1971. Studies on heterosis in
summer squash (Cucurbita pepo). Prog. Hort., 3(2): 5-15.
Janakiram, T. and P.S. Sirohi, 1991. Gene effects for fruit number in
bottlegourd (Lagenaria siceraria) Ann. Agric. Res., 12(2): 208210.
Sirohi, P.S., T.S. Kumar and B. Choudhary, 1986. Studies on combining
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